Hello Darren.
First of all you must notice is that RADIUS is one special snowflake and it does not have thing called Authorization as a separate thing. What it does have is the moment users get authenticated Radius server straight away sends the reply with all the authorization parameters. That just it. No other way. Authentication an Authorization are one when you talk RADIUS. So what you might need is get a bit of reading on how RADIUS works.
Second question regarding examples. You might want to look at Cisco VPN course which covers that subject of downloadable ACLs and Radius / Tacacs differences. In this course you will find the labs and examples of configuring downloadble ACL.
Regards Dmitriy Tsaryapkin.
P.S. Though there are several options there when you can created LDAP maps and map some attributes in AD to ACLs created localy on ASA. Not sure about VPN's but it worked for me with Cut-Through Proxy authentication with attributes taken from LDAP.